Tag Archives: REST

We believe Cloud Native development disciplines are essential regardless of the infrastructure.

Today, RackN announce very low entry level support for Digital Rebar Provisioning – the RESTful Cobbler PXE/DHCP replacement. Having a company actually standing behind this core data center function with support is a big deal; however…

We’re making two BIG claims with Provision: breaking DevOps bottlenecks and cloud native physical provisioning. We think both points are critical to SRE and Ops success because our current approaches are not keeping pace with developer productivity and hardware complexity.

I’m going to post more about Provision can help address the political struggles of SRE and DevOps that I’ve been watching in our industry. A hint is in the release, but the Cloud Native comment needs to be addressed.

First, Cloud Native is an architecture, not an infrastructure statement.

There is no requirement that we use VMs or AWS in Cloud Native. From that perspective, “Cloud” is a useful but deceptive adjective. Cloud Native is born from applications that had to succeed in hands-off, lower SLA infrastructure with fast delivery cycles on untrusted systems. These are very hostile environments compared to “legacy” IT.

What makes Digital Rebar Provision Cloud Native? A lot!

The following is a list of key attributes I consider essential for Cloud Native design.

Micro-services Enabled: The larger Digital Rebar project is a micro-services design. Provision reflects a stand-alone bundling of two services: DHCP and Provision. The new Provision service is designed to both stand alone (with embedded UX) and be part of a larger system.

Swagger RESTful API: We designed the APIs first based on years of experience. We spent a lot of time making sure that the API conformed to spec and that includes maintaining the Swagger spec so integration is easy.

Remote CLI: We build and test our CLI extensively. In fact, we expect that to be the primary user interface.

Security Designed In: We are serious about security even in challenging environments like PXE where options are limited by 20 year old protocols. HTTPS is required and user or bearer token authentication is required. That means that even API calls from machines can be secured.

12 Factor & API Config: There is no file configuration for Provision. The system starts with command line flags or environment variables. Deeper configuration is done via API/CLI. That ensures that the system can be fully managed by remote and configured securely becausee credentials are required for configuration.

Fast Start / Golang: Provision is a totally self-contained golang app including the UX. Even so, it’s very small. You can run it on a laptop from nothing in about 2 minutes including download.

CI/CD Coverage: We committed to deep test coverage for Provision and have consistently increased coverage with every commit. It ensures quality and prevents regressions.

Documentation In-project Auto-generated: On-boarding is important since we’re talking about small, API-driven units. A lot of Provisioning documentation is generated directly from the code into the actual project documentation. Also, the written documentation is in Restructured Text in the project with good indexes and cross-references. We regenerate the documentation with every commit.

We believe these development disciplines are essential regardless of the infrastructure. That’s why we made sure the v3 Provision (and ultimately every component of Digital Rebar as we iterate to v3) was built to these standards.

Server management interfaces stink. They are inconsistent both between vendors and within their own product suites. Ideally, Vendors would agree on a single API; however, it’s not clear if the diversity is a product of competition or actual platform variation. Likely, it’s both.

What is Redfish? It’s a REST API for server configuration that aims to replace both IPMI and vendor specific server interfaces (like WSMAN). Here’s the official text from RedfishSpecification.org.

Redfish is a modern intelligent [server] manageability interface and lightweight data model specification that is scalable, discoverable and extensible. Redfish is suitable for a multitude of end-users, from the datacenter operator to an enterprise management console.

I think that it’s great to see vendors trying to get on the same page and I’m optimistic that we could get something better than IPMI (that’s a very low bar). However, I don’t expect that vendors can converge to a single API; it’s just not practical due to release times and pressures to expose special features. I think the divergence in APIs is due both to competitive pressures and to real variance between platforms.

Even if we manage to a grand server management unification; the problem of interface heterogeneity has a long legacy tail.

In the best case reality, we’re going from N versions to N+1 (and likely N*2) versions because the legacy gear is still around for a long time. Adding Redfish means API sprawl is going to get worse until it gets back to being about the same as it is now.

Putting pessimism aside, the sprawl problem is severe enough that it’s worth supporting Redfish on the hope that it makes things better.

That’s easy to say, but expensive to do. If I was making hardware (I left Dell in Oct 2014), I’d consider it an expensive investment for an uncertain return. Even so, several major hardware players are stepping forward to help standardize. I think Redfish would have good ROI for smaller vendors looking to displace a major player can ride on the standard.

Redfish is GREAT NEWS for me since RackN/Crowbar provides hardware abstraction and heterogeneous interface support. More API variation makes my work more valuable.

One final note: if Redfish improves hardware security in a real way then it could be a game changer; however, embedded firmware web servers can be tricky to secure and patch compared to larger application focused software stacks. This is one area what I’m hoping to see a lot of vendor collaboration! [note: this should be it’s own subject – the security issue is more than API, it’s about system wide configuration. stay tuned!]

Sometimes I just need to feed the SEO monster for Erlang. In this case, I could not find a good post that described doing an Erlang http:request that posts with a json payload. This is to support the BDD (“Cucumber but really fast”) testing framework that I’ve included in Crowbar.